Sensors for sensing an environmental parameter are well known and used throughout our current environment. Only one of the many examples used in today's world may, for example, be a temperature sensor which may, for example, be applied in a car for providing temperature information to the driver of the car or to the on-board computer of the car. Such a sensor draws its power from the overall power system of the car and uses the on-board wiring to provide the sensed value to the display of the car or to the on-board computer. However, when sensing the environmental parameters in a remote location, the requirements to the sensor system are quite different.
Sensor systems having such requirements are, for example, used in a sensor mote. A sensor mote typically refers to a relatively small sensor with its own energy storage. Also typically the sensor mote is part of a wireless network via which the sensed environmental parameter is communicated to a remote computer. A motes-system is a plurality of sensor motes which together form a plurality of sensors for sensing the environmental parameter. Such motes-systems have been used in many diverse applications, from earthquake measurements to warfare.
Such known motes typically comprises a controller, transceiver, power source and one or more sensors. One example of environmental monitoring can be found in the NASA sensor web. This network comprises spatially distributed sensors that wirelessly communicate with each other. In this network, every mote sends out collected data to every other mote, so substantially every mote knows what is happening in the network. Alternatively, sensor networks may be configured to use GPS communication and/or may be configured to handle “Big” data sets.
Using such known sensor networks for environmental mapping or monitoring, the position of the individual motes should be known which requires extensive communication with the outside world, for example, via a Global Positioning System (further also indicated as GPS). However, in some remote environments, such as, for example, oil wells or sewer systems in cities, the GPS signal does not reach the individual motes and other means of measuring the environment parameter have to be found.